There are a variety of processes in which solid particles are separated from a flowing gas stream. These types of separations are particularly common in many chemical and combustion type processes.
U.S. Pat. No. 6,166,282 shows a fluid bed reaction process in which catalyst is flowed with gas feed and product. The catalyst particles are separated from the product using cyclone separators and the separated catalyst is returned back to the process.
U.S. Patent Publication No. 2003/0200864 describes an acoustic agglomeration system that is used to agglomerate small particles in order to make them easier to separate from flowing fluids. The agglomeration method involves applying an acoustic field to a fluid that contains small particles. This causes the particles to agglomerate, forming larger particles, and the larger particles are separated from the flowing fluid.
U.S. Pat. No. 5,419,877 is also directed to the use of acoustic force to remove particles from a gas stream. The patent indicates that cyclonic separators are typically used in high temperature environments to separate particles with diameters greater than 5 microns. An acoustic barrier separator is used to remove particularly small diameter fly ash and hazardous volatiles from high temperature gas emissions.
U.S. Pat. No. 6,224,652 discloses a method and device for agglomerating particles in a gaseous flow through an acoustical agglomeration chamber. The method includes extracting a portion of gaseous flow from the outlet of an acoustical agglomeration chamber. The extracted gaseous flow is then passed through a feedback-loop, and large particles are reinjected into the inlet of the chamber. The device includes a fan that accomplishes reinjecting the extracted gaseous flow back into the chamber.
There is a need for more efficient methods of separating small particles from reaction systems. Particularly needed are efficient methods of separating small catalyst particles from a gas and particle mixture, preferably in a fluidized bed catalytic system.